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// SPDX-License-Identifier: GPL-2.0
/*
* ops.dequeue() of this scheduler iterates the user DSQ it consumes
* tasks from with bpf_iter_scx_dsq, which takes the DSQ lock.
* On a kernel that still runs ops.dequeue() with that lock held, the
* iteration self-deadlocks the CPU - this test wedges the system on
* unfixed kernels instead of failing cleanly.
*
* Copyright (c) 2026 fangqiurong <fangqiurong@kylinos.cn>
*/
#include <scx/common.bpf.h>
char _license[] SEC("license") = "GPL";
UEI_DEFINE(uei);
#define TEST_DSQ_ID 1000
u64 dq_count;
s32 BPF_STRUCT_OPS_SLEEPABLE(dequeue_iter_init)
{
return scx_bpf_create_dsq(TEST_DSQ_ID, -1);
}
s32 BPF_STRUCT_OPS(dequeue_iter_select_cpu, struct task_struct *p,
s32 prev_cpu, u64 wake_flags)
{
return prev_cpu;
}
void BPF_STRUCT_OPS(dequeue_iter_enqueue, struct task_struct *p, u64 enq_flags)
{
scx_bpf_dsq_insert(p, TEST_DSQ_ID, SCX_SLICE_DFL, enq_flags);
}
void BPF_STRUCT_OPS(dequeue_iter_dispatch, s32 cpu, struct task_struct *task)
{
scx_bpf_dsq_move_to_local(TEST_DSQ_ID, 0);
}
void BPF_STRUCT_OPS(dequeue_iter_dequeue, struct task_struct *p, u64 deq_flags)
{
struct bpf_iter_scx_dsq it;
struct task_struct *t;
if (!bpf_iter_scx_dsq_new(&it, TEST_DSQ_ID, 0)) {
while ((t = bpf_iter_scx_dsq_next(&it)))
;
}
bpf_iter_scx_dsq_destroy(&it);
__sync_fetch_and_add(&dq_count, 1);
}
void BPF_STRUCT_OPS(dequeue_iter_exit, struct scx_exit_info *ei)
{
UEI_RECORD(uei, ei);
scx_bpf_destroy_dsq(TEST_DSQ_ID);
}
SEC(".struct_ops.link")
struct sched_ext_ops dequeue_iter_ops = {
.init = (void *)dequeue_iter_init,
.select_cpu = (void *)dequeue_iter_select_cpu,
.enqueue = (void *)dequeue_iter_enqueue,
.dispatch = (void *)dequeue_iter_dispatch,
.dequeue = (void *)dequeue_iter_dequeue,
.exit = (void *)dequeue_iter_exit,
.timeout_ms = 1000U,
.name = "dequeue_iter",
};
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